Process of cleaning a substrate for microelectronic applications including directing mechanical energy through a fluid bath and apparatus of same

ABSTRACT

An apparatus of cleaning a workpiece for microelectronic applications can include fixture to help position the workpiece. In one aspect the apparatus can include a tank and a transducer. In another aspect the apparatus can include a nozzle. The fixture, the tank, the nozzle, or any combination thereof can include an electrostatic dissipative material having a volume resistivity R v  not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm. In a particular embodiment, a process of cleaning includes directing mechanical energy through a fluid to help overcome energy binding a contaminant to the workpiece.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The following disclosure is a non-provisional application which claims priority to U.S. Provisional Application No. 61/020,658 filed Jan. 11, 2008, entitled “Process of cleaning a substrate for microelectronic applications including directing mechanical energy through a fluid bath and apparatus of same” and having named inventors Oh-Hun Kwon, Raymond H. Bryden, and Qiang Zhao, and further claims priority to U.S. Provisional Application No. 60/912,128 filed Apr. 16, 2007, entitled “Process of cleaning a substrate for microelectronic applications including directing mechanical energy through a fluid bath and apparatus of same” and having named inventors Oh-Hun Kwon, Raymond H. Bryden, and Qiang Zhao, applications of which are incorporated by reference herein in their entirety.

BACKGROUND

1. Field of the Disclosure

This disclosure pertains in general to semiconductor processing and, more specifically to directing mechanical energy through a fluid bath.

2. Description of the Related Art

Within the semiconductor processing arts, contamination control is a critical and ongoing problem. As the core component size is reduced with successive generations, contamination control remains an ongoing concern. Of particular concern is the elimination of particulate contamination from workpieces, such as semiconductor substrates, photomasks, and reticles.

One method of removing particulate contamination includes submerging the workpiece in a cleaning solution and applying ultrasonic or megasonic energy to help dislodge unwanted particles at the surface of the workpiece. However, the size of the particulate contamination of interest has reduced as the size of the electrical components formed has decreased with succeeding generations. Transfer of ultrasonic or megasonic energy to smaller particles is less efficient than with larger particles so more energy is applied to maintain cleaning efficiency as smaller particles are removed. Thus, at successive generations, smaller and more fragile structures along the surfaces of the workpieces are subjected to more energy, increasing the likelihood of process-induced damage during the cleaning process.

Accordingly, the industry continues to demand improved articles and processes for removing particulate contamination that will decrease the process-induced damage that occurs during cleaning a substrate for microelectronic application.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings.

FIG. 1 includes an illustration of cross-sectional view of a workpiece in a tank, according to one embodiment.

FIG. 2 includes an illustration of a cross-sectional view of a portion of a fixture, according to one embodiment.

FIG. 3 includes an illustration of a cross-sectional view of a portion of a tank, according to one embodiment.

FIG. 4 includes an illustration of a cross-sectional view of a plurality of workpieces in a tank, according to one embodiment.

FIG. 5 includes an illustration of a cross-sectional view of a workpiece in a tank, according to one embodiment.

FIG. 6 includes an illustration of a cross-sectional view of a workpiece on a fixture, according to one embodiment.

FIG. 7 includes a plot of weight loss as a function test cycle for samples and comparative samples according to one embodiment.

FIG. 8 includes a three-dimensional plot of surface resistance versus x and y position on a sample formed according to one embodiment.

FIG. 9 includes a three-dimensional plot of surface resistance versus x and y position on a sample formed according to one embodiment.

FIG. 10 includes a three-dimensional plot of surface resistance versus x and y position on a sample formed according to one embodiment.

FIG. 11 includes a three-dimensional plot of surface resistance versus x and y position on a sample formed according to one embodiment.

The use of the same reference symbols in different drawings indicates similar or identical items.

Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention. The use of the same reference symbols in different drawings indicates similar or identical items.

DETAILED DESCRIPTION

A cleaning process can include directing mechanical energy through a fluid to help dislodge a contaminant from a surface of a workpiece in the fluid bath. In one aspect, the fluid includes a fluid bath within a tank, and the tank includes an electrostatic dissipative (ESD) material. In another aspect, a fixture in contact with the workpiece while performing the cleaning process can include the electrostatic dissipative material. In still another aspect, the fluid is dispensed through a nozzle, and the nozzle includes the electrostatic dissipative material. Thus an electrical pathway to ground can be formed such that electrostatic charge formed during the cleaning can be dissipated without forming an arc that can damage the workpiece. Specific embodiments of the present disclosure will be better understood with reference to FIGS. 1 through 6.

As illustrated in FIG. 1, a workpiece 101 is immersed in a fluid 103 in a tank 107. The fluid 103 mechanically coupled with a transducer 109 can transfer mechanical energy 105 from the transducer 109 to the workpiece 101 such that the mechanical energy 105 is applied along a surface of the workpiece 101. A fixture 111 can be attached to the workpiece 101 and is configured to aid in positioning the workpiece 101.

A transducer 109 mechanically coupled with the fluid 103 in the tank 107 can be activated and mechanical energy 105 is supplied to the fluid 103 in the form of vibration. The vibration of the transducer 109 produces pressure waves within the fluid 103 traveling substantially along the surface of the workpiece 101. Such pressure waves can transfer mechanical energy to a contaminant on the surface of workpiece 101 to help overcome the energy binding the contaminant to the surface of the workpiece 101. A boundary layer can lie along the surface of the workpiece 101 and act to protect a portion of the contaminant from the pressure waves. For a given fluid 103 within the tank 107, the thickness of the boundary layer can changed with the frequency of the pressure waves, thus a higher frequency can be used to dislodge a smaller particle than a lower frequency substantially cannot dislodge. In another embodiment, the vibrational energy can have a magnitude sufficient to cause bubbles to form within the fluid 103. The formation and collapse of the bubbles within the fluid 103 can provide mechanical energy to help dislodge the contaminant from the surface of the workpiece 101.

The workpiece 101 includes a substrate having a feature size of not greater than 10 micron that is to be cleaned. In one embodiment, the workpiece 101 can include a semiconductor substrate, a photomask or reticle. The workpiece 101 can have a minimum feature size of not greater than 10 microns.

In a particular embodiment, the workpiece 101 can include a photomask or reticle used to form the electronic component. The photomask or reticle can be used to transmit, direct, attenuate or any combination thereof a wavelength or spectrum of radiation in order to locally regulate the dose of radiation of at the surface of a semiconductor substrate during formation of a patterned layer on a semiconductor substrate. Because the pattern on the mask or reticle can be optically reduced, in one embodiment, the minimum feature of the mask or reticle can be not greater than 10 microns. In another embodiment, the minimum feature size can be not greater than 5 microns, not greater than 2 microns, or even not greater than 1 micron. In a particular embodiment, the minimum feature size is on the photomask or reticle can be in a range of 1 to 5 times the dimension of the patterned image formed using the photomask or reticle. In another embodiment, the minimum feature size on the photomask or reticle is in a range of 4 to 5 times the dimension of the patterned image. For example, a photomask or reticle capable of forming a 1 micron feature size can have a minimum feature size in a range of 4 to 5 microns.

In another embodiment, the workpiece 101 can include a semiconductor substrate including a partially or fully formed electronic device. The workpiece 101 can include a patterned layer with a minimum feature size of not greater than 2 microns. In another embodiment, the minimum feature size can be not greater than 1 micron, not greater than 0.5 microns, not greater than 0.2 microns, or even not greater than 0.1 microns.

Contaminant on the surface of the workpiece 101 of at least one half the size of the minimum feature size can interrupt the patterned layer sufficiently to cause a defect. In one embodiment, the averaged size of a contaminant can be not less than 5 micron in diameter. In another embodiment, the averaged size of a contaminant can be not less than 2 microns, 1 micron, 0.5 microns, 0.25 microns, 0.1 microns, or even not less than 0.05 microns.

The workpiece 101 can include an insulating material, semiconductor material, a conducting material, or any combination thereof. In one embodiment, the workpiece 101 includes a semiconductor material. In a particular embodiment, the workpiece can include silicon, germanium, carbon, a compound semiconductor material, or any combination thereof. In another embodiment, the workpiece 101 includes an insulating layer and a patterned metal layer. In a particular embodiment, the workpiece 101 includes a layer transparent to a specific wavelength or spectrum of radiation and a patterned layer opaque to the same wavelength or spectrum of radiation.

The workpiece 101 can be placed within a fixture 111 prior to being placed in contact with the fluid 103 in a tank 107. In one embodiment, the fixture 111 is configured to be used with the tank 107 such that a workpiece 101 within the fixture 111 can be reliably located at a point with conditions conducive to performing the cleaning operation. In one embodiment, the fixture 111 is configured to help position the workpiece 101 with respect to the transducer 109, the tank 107, or any combination thereof.

The fixture 111 typically has a mass of material extending to and terminating at an exterior surface of the surface of the fixture 111, that mass of material being defined as an outer surface portion. The outer surface portion may be a distinct layer, or may be free of a well-defined interface or boundary with respect to the balance of the workpiece, as is the case with a monolithic structure. The outer surface portion can include a material chemically resistant to the fluid 103. Suitable materials can include carbides, nitrides, and oxides, or combinations or compound materials thereof. In one embodiment, the fixture 111 includes oxides such as Al₂O₃, SiO₂, Cr₂O₃, MgO, ZrO₂, TiO₂, Y₂O₃, and Fe₂O₃, and combinations or complex compounds thereof.

In a particular embodiment, the material includes silicon. In a more particular embodiment, the material includes silicon carbide. In such a case, the outer surface portion includes not less than about 20 vol % silicon carbide. Still, in another embodiment, the outer surface portion includes not less than about 50 vol %, not less than about 75 vol % SiC, not less than 95 vol %, or even not less than about 99.9 vol % SiC. According to one particular embodiment, the surface portion consists essentially of SiC.

In one embodiment, the outer surface portion has a volume resistivity (“R_(v)”) of not greater than 1E11 ohm-cm. In another embodiment, the outer surface portion includes electrostatic dissipative material having an R_(v) not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm. In a particular embodiment, the outer surface portion has an R_(v) in a range of approximately 1E5 to 1E10 ohm-cm. In another embodiment, the outer surface portion has an R_(v) in a range of approximately 9E5 to 9E8 ohm-cm. In a particular embodiment, the outer surface portion of fixture III can be electrically connected to the outer surface portion of tank 107 such that a charge formed on the workpiece 101 can be dissipated to the tank 107 without forming an arc. Details of the tank 107 are provided below.

The fixture III has a high Young's modulus, generally not less than about 50 GPa/cm³. In one particular embodiment, the Young's modulus is not less than about 60 GPa/cm³, not less than about 75 GPa/cm³, or even not less than about 100 GPa/cm³. Still, the Young's modulus is typically not greater than about 500 GPa/cm³.

In one embodiment, at least the outer surface portion of fixture III has a density of at least 80% of the theoretical value of the material of the outer surface portion. In another embodiment, the outer surface portion of fixture III has a density of at least 90%, of at least 95%, or even at least 98% of the theoretical value of the material of the outer surface portion.

In one embodiment, the outer surface portion of fixture 111 can have an average surface roughness (“R_(a)”) value of less than 100 microns. In another embodiment the outer surface portion of fixture III can have a R_(a) value less than 10 microns. In another embodiment, the R^(a) value can be less than 1 micron.

In a particular embodiment, the fixture 111 includes a homogeneous, monolithic composition of material. The fixture III can also be formed as a homogeneous, monolithic structure. The fixture III can be a single and integral mass of material, which is typically formed as one piece. In such a case, substantially the entire fixture 111 may have the above-disclosed R_(v), and density, R_(a) values.

In another embodiment, the fixture 111 can include a plurality of layers. For example, the fixture 111 includes a base layer 201 and a skin layer 203 overlying the base layer 201 along at least one major surface thereof, or both major surfaces, as illustrated in FIG. 2. In either case, the skin layer 203 defines the outer surface portion in such layered embodiments. In a particular embodiment, the base layer 201 lies in direct contact with the skin layer 203. Generally, the skin layer 203 includes at least a portion of the fixture 111 that can contact the substrate 101 when the substrate 101 would be cleaned.

The base layer 201 can include substantially any material that is capable of supporting the skin layer 203 and is compatible with the process of forming the skin layer 203. The base layer 201 can include an organic or inorganic material. The base layer 201 can include conducting material, semiconductor material, insulating material, or any combination thereof.

The skin layer 203 generally has an average thickness of not less than about 2.0 microns. In one embodiment, the average thickness of the skin layer 203 is not less than about 5.0 microns, not less than about 10 microns, or even not less than about 20 microns. In a particular embodiment, the skin layer 203 had a thickness in a range for approximately 5 to 100 microns.

The skin layer 203 can include not less than 1 percent of the total thickness of the fixture 111. In another embodiment, the skin layer 203 includes not less than 5 percent of the total thickness of the fixture 111. In still another embodiment, the skin layer 203 includes not less than 10 percent of the total thickness of the fixture 111. In yet another embodiment, the skin layer 203 includes not less than 20 percent of the total thickness of the fixture 111. In another embodiment, the skin layer 203 includes not less than 50 percent of the total thickness of the fixture 111.

In one embodiment, the skin layer 203 of the fixture 111 includes a material with a Young's Modulus not less than 390 GPa. In a particular embodiment the skin layer of fixture 111 includes a material with a Young's Modulus in a range of approximately 400 to 500 GPa. In a particular embodiment, the Young's Modulus of skin layer of the fixture 111 lies in a range of approximately 430 to 470 GPa.

In one embodiment, the fixture 111 can be formed using a process such as casting, molding, pressing, or extruding. In another embodiment, the skin layer 203 can be formed over the base layer 201. In a particular embodiment the skin layer 203 is deposited using a thick film deposition process, a thin film deposition process, or any combination thereof. A thick film deposition process can include an aerosol deposition, a liquid deposition, a plasma spray, a thermal spray, or any combination thereof. A thin film deposition process can include chemical vapor deposition, physical vapor deposition, atomic layer deposition, or any combination thereof. The skin layer 203 may or may not be cured after deposition. In another particular embodiment, the skin layer 203 is grown on the base layer 201. The base layer 201 can be placed in a reactive environment and a portion of the base layer 201 can be reacted to form the skin layer 203. In one embodiment, the base layer 201 is heated in the presence of a vapor or liquid material that can react with the surface portion of the base layer 201 to form the skin layer 203.

As illustrated in FIG. 3, the fixture 111 includes a base layer 301 and a skin layer 303 wherein the skin layer 303 overlies only one major surface of the base layer 301. The skin layer 303 is formed over a portion of the base layer 301 using a processing described with respect to other skin layers, herein. For example, the skin layer 303 can be formed over the portions of the fixture 111 that are configured to be wetted by the fluid 103 and not overlie the portions of the fixture 111 that are not configured to be wetted by the fluid 103. The base layer 301 and the skin layer 303 can include a same material, have a same property, be formed by a same embodiment, or have a same relative location with respect to each other as described for other base layers and skin layers, herein.

Again referring to FIG. 1, the fluid 103 can include a conductive or insulative fluid. The fluid 103 can include organic material, inorganic material, or any combination thereof. In one embodiment, the fluid can include an organic solvent. In another more particular embodiment, the fluid can include an alcohol, an ester, ether, amine, a ketone, a freon, or the like. In an alternative embodiment, the fluid 103 can include an inorganic material. Suitable inorganic fluids include water, and particularly can include an ionic aqueous solution. In a particular embodiment, the fluid 103 can include an alkaline aqueous solution (pH greater than approximately 9) or an acidic aqueous solution (pH of less than approximately 5). In one embodiment, the fluid 103 can help reduce the binding energy between a contaminant along the surface of the workpiece 101 and the surface of the workpiece 101 such that less energy is required to dislodge the contaminant from the surface of the workpiece 101.

The fluid 103 can flow relative to the substrate 101, the tank 107 or any combination thereof. Such flow provides a sweeping action to help entrain any contaminant dislodged from the surface of the workpiece 101. As illustrated, the fluid 103 can overflow the tank 107 such that contaminants dislodged from the workpiece 101 can be removed from that tank 107, reducing the likelihood of the contaminants being deposited at another location on the surface of the workpiece 101 after being removed. In one embodiment, the fluid 103 within the tank 107 has a turn over rate in a range of 0.1 volumes per minute to 20 volumes per minute. In a particular embodiment, the flow of the fluid 103 is selected such that the flow remains laminar during processing. In a more particular embodiment, the Reynolds' number that characterizes the flow of the fluid 103 through the tank 107 remains below 2100.

The transducer 109 can be activated such that mechanical energy is applied to the fluid 103 within the tank 107. In another embodiment, the mechanical energy includes a vibrational energy having a frequency in a range of 20 kHz to 2000 kHz. In a more particular embodiment, the vibrational energy has a frequency in a range of 500 kHz to 2000 kHz. In another embodiment, while the transducer 109 is activated, the fluid produces radiation in a spectrum with a peak between 250 to 300 nm. In a more particular embodiment, the fluid produces radiation spectrum with a peak between 279 to 290 nm.

In a particular embodiment, the relative motion of the fluid 103 and the surface of the workpiece 101 is capable of forming a static charge on the tank 107, workpiece 101, the fixture 111, or any combination thereof during the contaminant removal process. The amount of electrostatic charge produced during the cleaning process can be sufficient to produce an arc capable of damaging the workpiece 101 if not properly dissipated.

The tank 107 has an inside volume configured to confine the fluid 103. The walls that form tank 107 can have opposing major exterior surfaces, and are arranged such that one of the major exterior surfaces defines the interior volume of the tank and the other major exterior surface defines the exterior of the tank. The compositional, electrical, mechanical, and morphological properties of the walls can be as described above with respect to the fixture. For example, the walls have an outer surface portion extending to and defining at least one of the exterior surfaces of the walls. The outer surface portion of the walls typically has the compositional features, density, surface roughness, strength, resistivity features as described above with respect to the outer surface portion of the fixture 111. Like the fixture 111, the outer surface portion of the walls may be a discrete layer or an outer mass of material free of a distinct boundary, as in the case of monolithic structures.

The outer surface portion of the walls typically defines the interior of the tank 107, but may further define the exterior of the tank, and may even encapsulate the walls of the tank (i.e. forming substantially the entire outer surface of the walls of the tank.

The tank 107 can be appropriately sized to allow cleaning one or more workpieces 101 within the internal volume. In the illustrated embodiment, the tank 107 is sized for cleaning a single workpiece 101. The tank 107 includes sufficient fluid 103 such that substantially continuous fluid contact to the surface of workpiece 101 is formed when the workpiece 101 is placed within the tank 107.

Although illustrated in FIG. 1 with respect to cleaning a single workpiece 101, in an alternative arrangement, illustrated in FIG. 4, a plurality of workpieces 401 may be cleaned at substantially a same time. As illustrated in FIG. 4, a plurality of workpieces 401 are placed within a fixture 411 and immersed in a fluid 403 in a tank 407.

The fixture 411 can be configured to help position the workpieces 401, and particularly position the workpieces 401 relative to the transducer 409, the tank 407, or any combination thereof. The workpieces 401, the fluid 403, and the tank 407 can include a material and be formed by an embodiment as previously described with respect to other workpieces, the fluids, and tanks described herein. As such, the tank 407, the fixture 411, or any combination thereof can serve to dissipate charge formed on any of the workpiece 401 during removing the contaminant from the surface of each of the workpieces 401.

A transducer 409 can be coupled to the fluid 403 such that mechanical energy 405 can be transferred from the transducer 409 to the workpieces 401 in a manner according to an embodiment described, herein. In one embodiment, the transducer 409 is sized relative to the number of workpieces 401 to be cleaned so that a condition conducive to removing particles is present over a sufficient volume to include substantially all the workpieces 401.

In another alternative arrangement, illustrated in FIG. 5, a contaminant can be removed from a surface of one or more workpieces 501 with a fluid 103 flowing in a different direction from the direction of the mechanical energy 505. As illustrated in FIG. 5, one or more workpieces 501 are placed within a fixture 511 and immersed in a fluid 503 in a tank 507. The fixture 511 can be configured to help position one or more workpieces 501. The one or more workpieces 501, the fluid 503, fixture 511, and the tank 507 can include material and be formed using an embodiment as previously described with respect to other workpieces, fluids, fixtures, and tanks described herein. In a particular embodiment the fixture 511 or the tank 507 includes an electrostatic dissipative material.

The fluid 503 can transfer mechanical energy 505 from the transducer 509 to the workpiece 501 as described herein. The direction of flow of fluid 503 can be different from a direction of the mechanical energy 505 through the tank 507. As illustrated in FIG. 5, the direction of the mechanical energy 505 is substantially horizontal while the direction of the flow of the fluid 503 is substantially vertical. In such an arrangement, the tank 507, the fixture 511, or any combination thereof can serve to dissipate charge formed on any workpiece 501 while removing the contaminant from the surface of the workpiece 501.

According to another alternative arrangement, illustrated in FIG. 6, a top surface of a workpiece 601 is to be cleaned. A fixture 611 can lie within a cup 607 and be configured to help position a substrates 601 relative to a nozzle 613 configured to place the fluid on the top surface of the workpiece 601. The workpiece 601 is placed on the fixture 611 and a sheet of fluid 603 is applied to the surface of the workpiece 601 using a nozzle 613 such that a flow pattern is formed across the surface of the workpiece 601. The workpiece 601, the fixture 611, the fluid 603, or any combination thereof can include a same material and be formed by an embodiment as described for other workpieces, fixtures, or fluids herein.

In a particular embodiment, fixture 611 can include an outside surface portion including an electrostatic dissipative material. The outside surface portion of the fixture 611 can lie between the workpiece 601 and the remainder of the fixture 611. In a more particular embodiment, the outside surfaced portion of the fixture 611 is in direct contact with the backside of the workpiece 601. In another particular embodiment, the outside surface layer of the fixture 611 can be in communication with the nozzle 613, the cup 607, the fluid 603, electrical ground, or any combination thereof.

The nozzle 613 can include a material, have properties, or have a structure as previously described with respect to fixtures described herein. In a particular embodiment, the nozzle 613 includes an electrostatic dissipative material as described above with respect to the outer surface portion of the tanks walls and the fixture 111. In another particular embodiment, the nozzle 613 can be in communication with the fixture 611, the fluid 603, the cup 607, electrical ground, or any combination thereof.

As illustrated, the top surface of the workpiece 601 is oriented in a substantially horizontal orientation and the fluid 603 is applied to substantially cover the center of the workpiece 601. The fluid 603 can be placed at the center of the workpiece 601 a flow to the edge of the workpiece 601 and be captured with in the cup 607. The flow of the fluid 603 is sufficient to allow a contaminant released from the surface of the workpiece 601 to be swept away from the surface such that depositing of the contaminant on the surface of the substrate 601 again can be avoided. In one embodiment, the fixture 611 can be rotated on a shaft 615 causing the workpiece 601 to accelerate the fluid 603 in contact with the surface of the workpiece 601, affecting the flow across the surface of the workpiece 601.

The shaft 615 can be attached to the fixture 611 such that rotation of the shaft 615 causes the fixture 611 to rotate about the axis of the shaft 615. The shaft 615 can include materials typically used to form mechanical shafts, such as metals, metal alloys, or a combination thereof. In one embodiment, the shaft 615 can spin at not less than 100 RPM. In other embodiments, the shaft 615 can spin at not less than 500 RPM, not less than 1000 RPM, or even not less than 10000 RPM. Such motion can affect the volume and speed of the fluid 603 in contact with the surface of the substrate 601, thus affecting the ability of the fluid 603 to sweep the contaminant away from the surface of the substrate 601.

The fluid can flow off the edge of the workpiece 601 and be collected in the cup 607. The cup 607 can be formed of a material chemically resistant to the fluid 603. In one embodiment, the cup 607 can include an electrostatic dissipative material as described above. In a particular embodiment, the cup 607 can include a material, have a structure, and be formed using an embodiment described with respect to the tanks, herein. In a particular embodiment, the cup 607 can be in communication with the fixture 611, electrical ground, the fluid 603, the nozzle 613, or any combination thereof. Although not illustrated, the cup 607 can include a service connection, such as a drain, exhaust, or the like.

Optionally, the apparatus of FIG. 6 can also include a transducer 609. As illustrated, the transducer 609 can be configured to contact the fluid 603 and be spaced-apart from the workpiece 601. In one embodiment, the transducer 609 is configured to apply mechanical energy in a direction substantially perpendicular to the surface of the workpiece 601. In another particular embodiment, the magnitude of the mechanical energy produced by the transducer is reduced relative to the magnitude of the mechanical energy produced by the transducer 109 based on the relatively smaller volume of the fluid and closer distance from the transducer to the workpiece as compared to other arrangements described, herein. In another embodiment, the fixture 611 is configured to help locate the substrate 601 with respect to the transducer 609.

Thus, a contaminant can be removed from a workpiece for microelectronic applications. In one aspect, an apparatus of performing the clean can include a fixture to help position the workpiece, a tank and a transducer. In another aspect the apparatus can include a fixture and a nozzle. By using an electrostatic dissipative material having a volume resistivity R_(v) not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm as a portion of the fixture, the tank, the nozzle, or any combination thereof, an electrostatic charge formed during processing can be discharged without forming an arc that can damage the workpiece. In a particular embodiment, rotation of the fixture alters the flow across the workpiece mounted on the fixture.

Some specific embodiments are described below in the form of examples of forming electrostatic dissipative structures. As used with respect to the examples below, a structure for cleaning a substrate for microelectronic applications can include a tank, a fixture, or a nozzle.

EXAMPLE 1

An electrostatic dissipative monolithic structure for cleaning a substrate for microelectronic applications is made using the following process. Initially, submicron SiC (specific surface area 9.0 m²/g) powder is mixed with 20 wt % water to form a slurry. The slurry is then treated with an acid solution containing equal parts HNO₃ and HF acids. After 8 hours in the agitated acid treatment tanks, the slurry is diluted with DI water to decant the supernatant and the settled species is filter pressed to remove the water. The resulting filter cake exhibited about 72 wt % solids content.

The filter cake is refluidized with water until it has a solids content of about 60 wt %. After refluidizing, an addition of concentrated NH₄OH solution is provided to shift the pH above 8, which facilitates electrostatic dispersion. The slurry is then vibration milled with 10 mm SiC media, along with a 0.64 wt % addition of submicron B₄C and is milled for a minimum of 8 hours, until a mean particle size of 0.48 microns is achieved.

The resulting slurry is then mixed with 2.8 wt % phenolic resin and 3.0 wt % of both poly-vinyl alcohol and acrylic resin. The mixture is then spray dried to achieve a target nodule size of approximately 75 microns.

After spray drying, the granulates are dry pressed and cured at 250° C. for a duration of 2 hours to form a green-state (i.e., unfired) structure. The green-state structure is then fired at 2250° C. in a nitrogen atmosphere for a 4 hour soak time. The resulting monolithic structure has a density of 3.15 g/cc, exhibits less than 2.0 vol % porosity, and has a volume resistivity of 1.4E8 ohm-cm.

EXAMPLE 2

An electrostatic dissipative multilayered structure for cleaning a substrate for microelectronic applications is made using the following process. A mixture containing 10.5 wt % water, 43.0 wt % 100F SiC (d₅₀=150 microns), and 46.5 wt % fine SiC (d₅₀=3 microns) is blended at pH of 7.8. The pH is adjusted using a 25% solution of NaOH. The mixture is processed in a rolling mill for a minimum of 4 hours to achieve a good dispersion and homogeneous mixing. Latex is then added to the mix at a concentration of 0.2% by weight.

The resulting bimodal slurry is then cast into a plaster of Paris mold incorporating a cavity having roughly the desired structure dimensions. When consolidation is complete, the part is stripped from the mold and dried at 60° C. for a minimum of 8 hours to form a green article. After drying, the green article is fired at a temperature of 2450° C. in an argon atmosphere with a soak time of 8 hours to form a base layer.

After firing the green article, the structure is coated with a layer of plasma sprayed Cr₂O₃ to form a skin layer having a thickness of 150 microns. Forming the skin layer results in closing the porosity at the surface, making the article smoother and denser than before the skin layer is formed. The resulting volume resistivity (R_(v)) of the electrostatic dissipative skin layer of the multilayered structure is 2.4E7 ohm-cm.

COMPARATIVE EXAMPLE 1

A comparative non-electrostatic dissipative monolithic structure for cleaning a substrate for microelectronic applications is made using the following process. The process for forming the structure in Example 2 is followed, except that after firing the green article, the structure is not coated with a layer of plasma sprayed Cr₂O₃ and no skin layer is formed. This results in and article with a fired density of 2.75 g/CC having a 15% open porosity. The resulting volume resistivity (R_(v)) of the monolithic structure is 2E3 ohm-cm.

COMPARATIVE EXAMPLE 2

A comparative non-electrostatic dissipative multilayered structure for cleaning a substrate for microelectronic applications is made using the following process. The process for forming the structure in Comparative Example 1 is followed to form a base layer. After firing the green article, the structure is coated with a layer of chemically vapor deposited (CVD) silicon carbide to form a skin layer having a thickness of 150 microns. This results in closing the porosity at the surface of the base layer, making the article smoother and denser than before skin layer is formed. The resulting volume resistivity (R_(v)) of the non-electrostatic dissipative skin layer of the multilayered structure is 1E2 ohm-cm.

While the foregoing examples detail particular methods of forming certain structures, the following Comparative Examples detail the corrosion resistance and mass loss reduction of such structures as compared to conventional materials. According to certain embodiments, silicon carbide can be particularly useful as an electrostatic dissipative material and accordingly for use within the fixture 411 and other components for cleaning workpieces (e.g., a nozzle or tank walls). In accordance with a particular embodiment and as illustrated in the data provided herein, silicon carbide materials described herein demonstrate improved leaching resistance and reduced total mass loss or reduced volume loss over conventional materials when exposed to typical cleaning procedures and cleaning materials. In the following examples, the Samples 1-4 were made according to the processes disclosed in Example 1.

TABLE 1 Cleaning Sample Weight Loss Sample Test (mg) Sample 1 Piranha 0.0 Sample 2 Piranha 0.0 Conventional 1 Piranha 0.0 Conventional 2 Piranha 0.1 Sample 3 SC-1 0.2 Sample 4 SC-1 0.1 Conventional 3 SC-1 1.1 Conventional 4 SC-1 0.9

Table 1 provided above illustrates the total mass loss of samples comprising silicon carbide electrostatic dissipative (ESD) material described herein (Samples 1-4) as compared to conventional quartz materials (Conventional 1-4). Two different cleaning tests were used to test the general chemical resistance of the samples, a Piranha cleaning test and SC-1. The Piranha cleaning test included exposing each of the samples to 20 ml of a 3:1 concentration of H₂SO₄:H₂O₂ by volume within a sealed container. After sealing the samples within the container, the samples were heated up to 200° C. over 10 minute duration and held at 200° C. for 30 minutes. The SC-1 cleaning test included exposing each of the samples to 20 ml of a 5:1:1 concentration H₂O:H₂O₂:NH₄OH by volume within a sealed container. After sealing the samples within the container, the samples were heated up to 150° C. over 10 minute duration and held at 150° C. for 30 minutes.

Notably, the total mass loss for Samples 1-4 demonstrated in Table 1 is less than the conventional samples. In particular, Table 1 illustrates that for the SC-1 test, Sample 3 and Sample 4 had a mass loss that was almost an order of magnitude less than Conventional Samples 3 and 4. It will be appreciated that lower mass loss of components used within the cleaning apparatus reduces the likelihood of contamination of the workpieces being cleaned and also improves the lifetime of the cleaning apparatus and components.

By way of further comparison, Samples 1-4 had a starting mass of 11.0 g each, while the Conventional Samples 1-4 each had a starting mass of 7.58 g. By comparison, Samples 3-4 that were subject to the SC-1 cleaning test lost 0.002% and 0.0001% of the total mass of the samples respectively. The Conventional Samples 3-4 subject to the SC-1 cleaning test lost 0.01% and 0.01% of the total mass of each of the samples respectively. By comparison, the percentage mass lost by the Conventional Samples 3-4 was typically an order of magnitude greater.

Referring to Table 2 below, a repetitive exposure test was conducted on two samples from each group. As provided in Table 2, each of the samples are subjected to two consecutive cleaning tests of the same type (i.e., Piranha or SC-1 as described above) to determine the corrosion resistance of the samples to repetitive cleaning processes.

TABLE 2 Sample Weight Loss Sample Weight Loss Cleaning (mg) (mg) Sample Test 1st Test Cycle 2nd Test Cycle Sample 1 Piranha 0.00 0.00 Sample 3 SC-1 0.15 0.20 Conventional 1 Piranha 0.05 0.15 Conventional 3 SC-1 1.00 1.95

Sample 1 demonstrated no mass loss after two consecutive cleaning processes as compared to the Conventional Sample 1 that demonstrated incrementally increasing weight loss with subsequent exposure to the cleaning solution in the second test cycle. Additionally, Sample 3 demonstrated far less weight loss than the comparative Conventional Sample 3, and in fact, after two consecutive cleaning processes, Sample 3 demonstrated a weight loss of almost an order of magnitude less than the Conventional Sample 3.

Moreover, FIG. 7 is provided to illustrate the mass loss of each of the samples of Table 2 as a function of the cleaning test cycle. As more clearly illustrated in FIG. 7, Sample 3 initially demonstrated a weight loss at one rate (the slope of the line) after the first cycle, however, upon exposure to the second test cycle, the rate of mass loss for Sample 3 actually decreased. By comparison, after two consecutive test cycles, the Conventional Sample 3 demonstrated an almost linear mass loss.

Table 3 provided below, indicates mass loss for particular elements leached by each of the samples after subject to one of the two cleaning tests. After each of the samples were subject to a cleaning test, the cleaning solution was analyzed using inductively coupled plasma (ICP) spectrometry to determine the elemental components and the amount of the components that leached from each of the samples during exposure to the cleaning solution.

TABLE 3 Sample Cleaning Sample 1 Sample 2 Conv. 1 Conv. 2 Sample 3 Sample 4 Conv. 3 Conv. 4 Test Piranha SC-1 Element microgram per treated sample Al 0.05 0.05 0.5 0.2 0.1 0.15 0.3 1.2 B 0.95 0.9 <0.05 <0.05 0.5 0.45 <0.05 <0.05 Ca 0.5 0.45 1.05 0.9 0.95 0.6 1 0.85 Fe 0.85 1.2 0.35 0.65 <0.1 0.2 0.15 0.2 Mg <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 0.04 0.05 Na <0.4 <0.4 0.6 <0.4 <0.4 <0.4 <0.4 <0.4 Si 2.35 2.4 3.3 3.1 10.9 8.5 660 360 Ti 0.25 0.2 0.1 <0.05 0.29 0.25 0.05 0.05 V 0.4 0.4 <0.05 <0.05 0.6 0.5 <0.05 <0.05 weight 0 0 0 0.1 0.2 0.1 1.1 0.9 loss [mg]

With regard to the samples analyzed under the Piranha cleaning test conditions, the Samples 1 and 2 lost a greater mass content of B, Fe, Ti, and V as compared to the Conventional Samples 1 and 2. While the Conventional Samples 1 and 2 lost a greater mass content of Al, Ca, and Si as compared to the Samples 1 and 2. Notably, leaching of particular elements, such as transition metals Fe and Ti in the case of Samples 1 and 2, may be more or less harmful to the workpiece being cleaned depending upon the intended application of the workpiece. For example, workpieces that include electrical components, such as a semiconductor wafer, may have very particular levels of dopants and leaching of certain species into the cleaning solution may contaminate the workpiece.

With regard to the samples analyzed under the SC-1 cleaning test conditions, Samples 3 and 4 demonstrated less total mass loss as compared to the Conventional Samples 3 and 4. Additionally, Samples 3 and 4 demonstrated a greater mass loss of elements such as B, Ti, and V as compared to Conventional Samples 3 and 4. Unlike the Samples 1 and 2 tested under the Piranha cleaning conditions, Samples 3 and 4 and Conventional Samples 3 and 4 had a substantially equal mass loss of Fe and Ca. Moreover, the Conventional Samples 3 and 4 demonstrated a greater mass loss content of elements Al, Mg, and Si as compared to the Samples 3 and 4. Most notably, the mass loss of elemental Si from the Conventional Samples 3 and 4 is at least 30 times greater than the mass loss of Si from Samples 3 and 4. As described above, mass loss of particular species may or may not be desirable depending upon the intended application and design of the workpiece, however, significant mass loss of any species may be undesirable as it indicates low corrosion resistance and reduced lifetime.

Table 4 provided below, indicates mass loss for particular elements leached by each of the samples after subject to a second subsequent cleaning test. Like before, for each of the samples, the cleaning solution was analyzed using inductively coupled plasma (ICP) spectrometry.

TABLE 4 Sample Cleaning Sample 1 Sample 2 Conv. 1 Conv. 2 Sample 3 Sample 4 Conv. 3 Conv. 4 Test Piranha SC-1 Element microgram per treated coupon Al 0.9 <0.05 0.15 0.3 <0.05 <0.05 0.2 0.3 B 1.05 0.85 0.25 0.25 0.25 0.25 <0.05 <0.05 Ca 0.75 0.5 0.55 0.5 0.55 0.4 1.6 1.2 Fe <0.1 <0.1 <0.1 <0.1 <0.1 0.19 <0.1 <0.1 Mg <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 0.03 Na <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 Si 1.05 1.35 1.6 1.5 5.5 5 430 410 Ti <0.05 <0.05 0.15 <0.05 <0.05 <0.05 <0.05 <0.05 V <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 weight 0 0 N/A 0.1 0 0.1 1 0.9 loss [mg]

A comparison of Tables 3 and Table 4 can provide additional information on the corrosion resistance for repetitive exposure to corrosive cleaning solutions. With regard to the samples analyzed under the Piranha cleaning test conditions, Samples 1 and 2 lost a greater mass of B as compared to the Conventional Samples 1 and 2. While by comparison, the Conventional Samples 1 and 2 lost a greater mass content of Si as compared to the Samples 1 and 2. Notably, unlike the initial cleaning test cycle provided in Table 3, after the second cleaning test cycle, the Samples 1 and 2 demonstrated far less mass loss of Fe, Ti, and V, such that the mass loss content of these elements are substantially the same as the Conventional Samples 1 and 2, suggesting that there is an initial leaching of certain elements that occurs within Samples 1 and 2, and after an initial exposure to the cleaning solution, the leaching of these elements is reduced.

With regard to the samples analyzed under the SC-1 cleaning test conditions, Samples 3 and 4 demonstrated far less total mass loss overall. Notably, the Samples 3 and 4 demonstrated a greater mass loss of B as compared to Conventional Samples 3 and 4. However, the Conventional Samples 3 and 4 demonstrated a greater mass loss of Al, and a significantly greater mass loss of Si. In fact, in comparison to the data of Table 3, the loss of Si for the Conventional Sample 4 was greater after the second cleaning test cycle than in the first. By comparison, the mass loss of elemental Si in Conventional Samples 3 and 4 was at least 80 times greater than the mass loss of elemental Si from Samples 3 and 4.

Moreover, Samples 3 and 4 generally demonstrated a lower mass loss of all elemental species after the second cleaning test cycle as compared to the first cleaning test cycle (Table 3). Again, such data may suggest that Samples 3 and 4 undergo a greater leaching of elements upon an initial exposure to the cleaning solution, and after the initial exposure, the leaching of elements is reduced. The reduction of certain elemental species, such as transition metals, may be particularly suitable for providing a cleaning apparatus capable of cleaning highly sensitive electronic components, such as semiconductor wafers, and the like.

The foregoing Comparative Examples demonstrate the corrosion resistance and mass loss of samples made according to embodiments herein. The following examples include data and examples demonstrating the electrical properties of samples made according to embodiments described herein. In particular, the following examples provide electrical characterization data for samples incorporating ESD materials formed according to the processes provided in Examples 1 and 2.

Generally, ESD components have a surface resistance suitable for dissipating charge. More particularly, ESD components for use in cleaning apparatuses, for example, fixtures, nozzles, and tank walls as described herein may have particular surface resistances. As such, in accordance with embodiments herein, ESD components typically have a surface resistance within a range between about 1E5 ohms and about 1E11 ohms. In another more particular embodiment, the surface resistance is within a range between about 1E6 ohms and about 1E9 ohms.

Additionally, uniformity of surface resistance values across an available surface area of a component incorporating an ESD materials can be particularly useful for components expected to dissipate static electricity. The components using ESD materials described herein, generally have a surface resistance uniformity measured by the relative standard deviation of numerous surface resistance measurements made across the available surface of the component. Herein, relative standard deviation was calculated by dividing the actual standard deviation by the average surface resistance value and multiplying by 100 to form a percentage. As such, in accordance with one embodiment, the relative standard deviation of the surface resistance is not greater than about 25%. In another embodiment, the relative standard deviation is less, such as not greater than about 20%, such as not greater than about 15%, not greater than about 12%, or even not greater than about 8%. Still, in accordance with one particular embodiment, the relative standard deviation of surface resistance for the components incorporating ESD material is within a range between about 2% and about 20% and more particularly within a range between about 3% and about 15%.

Referring now to examples of surface resistance, Table 5 below illustrates the average surface resistance measured at 25 locations across the surface of two samples (Samples A and B) having a surface area of 16 in². The samples were measured by a Prostat PRS-801 meter with PRF-912 222 probe. The samples were made according to the process provided in Example 2.

Table 5 below provides each of the individual resistance measurements at different locations across the surface of the Samples A and B. Additionally, Table 5 includes in the last two rows, average surface resistance values and the relative standard deviation for the samples. As illustrate, Sample A demonstrated an average surface resistance of 5.27E+06 ohms and a relative standard deviation of 13.50%, while Sample B had an average surface resistance of 6.54E+06 ohms and a relative standard deviation of 14.30%. Accordingly, Samples A and B have substantially the same surface resistance as compared between the two samples. Samples A and B also have substantially uniform surface resistance values across the surface of the samples, as indicated by the relative standard deviation values.

TABLE 5 Resistance Resistance (Ohms) (Ohms) Sample A Sample B 5.90E+06 6.10E+06 5.50E+06 7.00E+06 4.40E+06 6.80E+06 6.00E+06 6.40E+06 6.80E+06 6.40E+06 5.30E+06 5.70E+06 5.10E+06 5.60E+06 4.10E+06 5.00E+06 5.40E+06 5.70E+06 6.10E+06 6.90E+06 5.50E+06 4.10E+06 5.00E+06 4.90E+06 5.00E+06 5.00E+06 5.40E+06 5.50E+06 5.80E+06 6.40E+06 5.60E+06 4.80E+06 4.80E+06 4.60E+06 4.40E+06 6.00E+06 5.40E+06 6.20E+06 5.80E+06 6.70E+06 5.50E+06 5.10E+06 6.80E+06 5.50E+06 6.30E+06 5.10E+06 6.50E+06 6.30E+06 7.00E+06 7.10E+06 5.27E+06 6.54E+06 13.50% 14.30%

FIGS. 8 and 9 provide three-dimensional illustrations of the surface resistance measurements as a function of position on the surface of the Samples A and B. FIG. 8 illustrates the surface resistance measurements of Sample A and FIG. 9 illustrates the surface resistance measurements of Sample B. FIGS. 8 and 9 more clearly illustrate the high degree of uniformity in surface resistance for Samples A and B as illustrated by the substantially planar nature of the surfaces.

Table 6 below illustrates the average surface resistance measured at 25 locations across the surface of two samples (Samples C and D) having a surface area of 16 in². The samples were measured by a Prostat RPS-801 meter with the PRF-912 222 probe. Samples C and D were made according to the process described in Example 1.

Table 6 below includes individual resistance measurements at different locations across the surface of the Samples C and D. Additionally, the last two rows of Table 5 provide average surface resistance values and the relative standard deviation for the samples. As shown, Sample C has an average surface resistance of 4.09E+07 ohms and a relative standard deviation of 12.64%, while Sample D has an average surface resistance of 7.11E+07 ohms and a relative standard deviation of 9.74%. Accordingly, Samples C and D demonstrated substantially the same surface resistance values as compared between the two samples. Moreover, Samples C and D demonstrated substantially uniform surface resistance values across the surface of the samples as shown by the low relative standard deviation values. Moreover, in a comparison of Table 5 and 6, the Samples C and D have a significantly higher average surface resistance than Samples A and B, such that it is generally order of magnitude difference.

TABLE 6 Resistance Resistance (Ohms) (Ohms) Sample C Sample D 2.80E+07 6.60E+07 3.10E+07 5.50E+07 3.30E+07 6.60E+07 4.00E+07 7.50E+07 4.20E+07 7.80E+07 4.30E+07 7.50E+07 3.40E+07 6.30E+07 3.70E+07 7.20E+07 4.40E+07 7.30E+07 4.60E+07 7.10E+07 4.30E+07 7.30E+07 4.00E+07 7.10E+07 3.70E+07 7.80E+07 4.60E+07 7.90E+07 4.80E+07 8.30E+07 4.30E+07 6.80E+07 4.40E+07 6.20E+07 4.10E+07 7.60E+07 4.30E+07 7.40E+07 4.10E+07 8.10E+07 4.40E+07 6.50E+07 4.00E+07 5.90E+07 4.00E+07 6.70E+07 4.50E+07 7.30E+07 4.90E+07 7.40E+07 4.09E+07 7.11E+07 12.64% 9.74%

FIGS. 10 and 11 provide three-dimensional illustrations of the surface resistance measurements as a function of position on the surface of the Samples C and D. FIG. 10 illustrates the surface resistance measurements as a function of position along the Sample C, and FIG. 11 illustrates the surface resistance measurements as a function of position along a surface of Sample D. FIGS. 10 and 11 more clearly illustrate the high degree of uniformity in surface resistance for Samples C and D. Additionally, a comparison of FIGS. 8 and 9 with FIGS. 10 and 11 further illustrate that Samples C and D have generally a higher surface resistance as compared to Samples A and B.

In accordance with other embodiments, the components described herein incorporating an ESD material, can have a decay time that is particularly useful for dissipating electrostatic charges. Generally, the decay time is an indicator of the time necessary to dissipate a particular voltage applied to a component. In accordance with one embodiment, the decay time of an ESD material as described herein is less than about 500 ms. In another embodiment, the decay time is less, such as less than about 250 ms or less than about 100 ms. Still, in accordance with a particular embodiment, ESD materials herein have a decay time within a range between about 1 ms and about 100 ms.

Table 7 below provides decay time values for two samples formed according to processes disclosed herein. In particular, Samples E and F were formed according to the process described in Example 1 above, with the exception that Sample E was fired in Ar at 2250° C. instead of N₂ as described above, and Sample F was fired in a N₂. As shown in Table 7, Samples E and F were subject to two different decay time tests, one measured as the decay time from 900V to 50V, while the other measuring the decay time from 100V to 10V. Moreover, the samples generally had a square or rectangular shape having two major surfaces and in each of the tests, both surfaces were tested as indicated in Table 7. As provided in Table 7, both Samples E and F demonstrate suitable decay times for use as ESD components, and particularly ESD structures used in cleaning apparatuses as described herein.

TABLE 7 900 V to 50 V decay 100 V to 10 V decay time (ms) time (ms) Sample Surface 1 Surface 2 Surface 1 Surface 2 Sample E 28.0 28.0 9.6 11.5 Sample F 35.4 50.9 260.5 454.7

Table 8 provide volume resistivity measurements for Samples E and F over different temperatures ranging from room temperature (R.T.) to 500° C. Each of the samples were heated in an Argon-containing atmosphere and were measured using a 2 point probe method. As provided in Table 8, each of the samples had a decrease in the volume resistivity as the temperature increased, however, each of the samples maintained a significant volume resistivity up to a temperature of 200° C. In particular, Sample F maintained a significant volume resistivity for temperatures in excess of 500° C. Such high temperature volume resistivities may be particularly desirable for applications providing heat to workpieces while cleaning.

TABLE 8 Volume resistivity (ohm-cm) Sample R.T. 100° C. 200° C. 300° C. 400° C. 500° C. Sample E 6.E+06 1.E+06 2.E+03 N.A. N.A. N.A. Sample F 1.E+08 3.E+07 6.E+06 3.E+05 6.E+03 1.E+03

Table 9 below provides volume resistivity measurements for Samples E and F over different voltages ranging from 0.1 V to 500 V. Each of the samples were measured using a 2 point probe method. As provided in Table 9, each of the samples substantially maintained their volume resistivity over the range of voltages. In particular, Sample F demonstrated substantially the same volume resistivity over the entire range of voltages tested. The ability of an ESD material to maintain its volume resistivity over a broad range of voltages may be suitable for dissipating charges and improved durability. In particular, ESD materials having the particular volume resistivities disclosed herein and having the ability to maintain such volume resistivity over a range of voltages are suitable for incorporation into components within cleaning apparatuses as described herein.

TABLE 9 Volume resistivity (ohm-cm) Sample 0.1 V 1 V 10 V 100 V 500 V Sample E 2.E+06 2.E+06 2.E+06 2.E+06 N.A. Sample F 6.E+09 6.E+09 3.E+09 4.E+08 6.E+07

In accordance with other embodiments, the components described herein incorporating an ESD material, can have a particular dielectric constants and dissipation factors particularly useful for use in dissipating electrostatic charges. Such dielectric constants and dissipation factors can be measured over a range of frequencies, for example from 1 Hz to 1 MHz. With regard to the dielectric constant, suitable values for ESD materials used in components herein is typically not greater than about 200. In other embodiments, the dielectric constant can be less, such as not greater than about 175, not greater than about 150, not greater than about 100, not greater than about 50, or even not greater than about 10 for the range of frequencies. Moreover, the dissipation factor for ESD materials described herein can be not greater than about 0.5. In accordance with other embodiments, the ESD material can have a dissipation factor of not greater than about 0.4, not greater than about 0.3 or even not greater than about 0.2 over a range of frequencies.

Table 10 below provides dielectric constant and dissipation factor information and corresponding relative standard deviation of the measurements for Samples E and F. The dielectric constant and dissipation factor for each of the samples were measured at two different frequencies. As provided, Samples E and F had dielectric constants less than 200 for each of the different frequencies. In particular, Sample F demonstrated a dielectric constant substantially less than the Sample E and less variation in the measurements. With regard to the dissipation factor, both samples illustrated a dissipation factor less than 0.5 with little variation. The dielectric constant and dissipation factor measurements of Samples E and F are suitable for use in ESD applications.

TABLE 10 Dielectric constant Dissipation factor Sample at 1 kHz at 1 MHz at 1 kHz at 1 MHz Sample E 162.0 ± 15.0 175.0 ± 14.0 0.17 ± 0.02 0.02 ± 0.01 Sample F 25.5 ± 1.0 89.3 ± 0.1 0.26 ± 0.00 0.41 ± 0.00

While the disclosed method and structure have been illustrated and described in the context of specific embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the scope of the present invention. For example, additional or equivalent substitutes can be provided and additional or equivalent production steps can be employed. As such, further modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the scope of the invention as defined by the following claims. 

1. A method of cleaning a workpiece for microelectronic applications, comprising: providing a workpiece in a fluid bath contained in a tanks the workpiece having first and second opposite major surfaces and a plurality of features formed on the first major surface, the features having a minimum feature size of not greater than 10.0 microns, wherein the tank is comprised of electrostatic dissipative material having a volume resistivity R_(v), not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm; and directing mechanical energy through the fluid bath to help overcome an energy binding a contaminant to the first major surface of the workpiece.
 2. The method of claim 1, wherein the tank is formed of a plurality of walls defining therein an internal volume, the walls having an outer surface portion that is comprised of said electrostatic dissipative material.
 3. (canceled)
 4. The method of claim 2, wherein the walls include a base and the outer surface portion is in the form of a skin layer, the skin layer forming the exterior portion of the walls and comprised of said electrostatic dissipative material.
 5. The method of claim 4, wherein the skin layer is not less than 10 um thick. 6-14. (canceled)
 15. The method of claim 1, further comprising placing the workpiece on a fixture in the fluid bath, the fixture being in communication with the tank to permit dissipation of electrostatic charges to the tank.
 16. The method of claim 15, wherein the fixture comprises electrostatic dissipative material having a volume resistivity R_(v), not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm. 17-22. (canceled)
 23. The method of claim 1, wherein directing mechanical energy through the fluid includes directing mechanical energy having a frequency in a range of approximately 20 to approximately 2000 kHz. 24-25. (canceled)
 26. A method for cleaning a workpiece for microelectronic applications, comprising: providing a workpiece in contact with a fluid and a fixture, the workpiece having first and second opposite major surfaces and a plurality of features formed on the first major surface, the features having a minimum feature size of not greater than 10 microns, wherein the fluid is in contact with the first major surface, the fixture is in contact with the second major surface, and the fixture is comprised of electrostatic dissipative material having a volume resistivity R_(v), not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm; and directing mechanical energy through the fluid to help overcome an energy binding a contaminant to the first major surface of the workpiece.
 27. The method of claim 26, wherein the fixture further includes an outer surface portion adjacent to the second surface of the workpiece that is comprised of said electrostatic dissipative material.
 28. (canceled)
 29. The method of claim 27, wherein the fixture include a base and the outer surface portion is in the form of a skin layer, the skin layer forming the exterior portion and comprised of said electrostatic dissipative material. 30-39. (canceled)
 40. The method of claim 26, further comprising placing the workpiece on the fixture in a tank, the fixture being in communication with the tank to permit dissipation of electrostatic charges to the tank. 41-50. (canceled)
 51. An apparatus for cleaning a workpiece for microelectronic applications, the apparatus including a tank comprising a plurality of walls defining therein an internal volume, the walls have an outer surface portion comprising electrostatic dissipative material having a volume resistivity R_(v), not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm. 52-53. (canceled)
 54. The apparatus of claim 51, wherein the outer surface portion has a density not less than 95% of theoretical density.
 55. The apparatus of claim 51, wherein the outer surface portion has a surface roughness R_(a) not greater than 100 microns. 56-57. (canceled)
 58. The apparatus of claim 51, further comprising a surface resistance uniformity having a relative standard deviation of not greater than about 25%.
 59. (canceled)
 60. The apparatus of claim 51, further comprising a decay time value of less than about 500 ms.
 61. (canceled)
 62. The apparatus of claim 51, further comprising a dielectric constant of not greater than about
 200. 63. (canceled)
 64. The apparatus of claim 51, further comprising a dissipation factor of greater than about 0.5.
 65. An apparatus of cleaning a workpiece for microelectronic applications, the apparatus including a fixture having an outer surface portion comprising electrostatic dissipative material having a volume resistivity R_(v) not less than 1E5 ohm-cm and not greater than 1E11 ohm-cm.
 66. The apparatus of claim 65, wherein the fixture include a base and the outer surface portion is in the form of a skin layer.
 67. The apparatus of claim 65, wherein the outer surface portion comprises silicon carbide.
 68. The apparatus of claim 65, wherein the outer surface portion has a density not less than 95% of theoretical density.
 69. The apparatus of claim 65, wherein the outer surface portion has a surface roughness R_(a) not greater than 100 microns. 70-71. (canceled)
 72. The apparatus of claim 65, further comprising a surface resistance uniformity having a relative standard deviation of not greater than about 25%.
 73. (canceled)
 74. The apparatus of claim 65, further comprising a decay time value of less than about 500 ms. 75-100. (canceled) 